Gas tube controlled relay circuits



June 1, 1948. w. J. oBRn-:N 2,442,430

GAS TUBE coNTHoLLED RELAY CIRCUITS Filed April l0, 1941 3 Sheets-Sheet 1 Annu IUI

June l, 1948. w. J, oBRlEN GAS TUBE CONTROLLED RELAY CIRCUITS 3 Sheets-Sheet 2 Filed April l0, 1941 lJune 1, W L QBRIEN 2,442,430

GAS TUBE CONTROLLED` RELAY CIRCUITS Filed April l0, 1941 3 Sheets-Sheet 3 Patented June l, 1948 2,442,430 GAS TUBE CONTROLLED RELAY CIRCUITS William J. OBrien, Chicago,

Edward F. Andrews,

Ill., assigner to Chicago, Ill.

Application April 10, 1941, Serial No. 387,908 22 Claims. (Cl. 175-320) The present invention relates to improvements in circuits including fast operating, low impedance relays, and more particularly to circuits wherein said relays are controlled by means of gas tubes.

The present invention relates also to the provision of new and improved circuit arrangements for preventing deleterious eilects resulting from oscillations in circuits including gas tubes, fast operating, low impedance relays, and condensers utilized to provide the relays with current impulses to increase the rapidity of operation thereof.

This invention relates also to the provision of new and improved gas tubes, and more specifically to the provision of gas tubes having an auxiliary anode by means of which the gas in the tube is maintained ionized and the tube conductive in spite of fluctuations in anode potential to values below that at which the gas would be deionized and the tube rendered non-conductive.

This invention relates also to the provision of new and improved control circuits including fast operating relays and gas tubes energized for relatively long periods of time, wherein the consumption of power is reduced without sacrificing efficiency or speed of operation of the relays.

The present invention further relates to the provision of a new and improved stop-on-carrier control for radio receivers, certain forms of which are disclosed and claimed in the Edward F. Andrews patents, Nos. 2,262,218, granted November 1l, 1941, and 2,326,737, granted August 7, 1943, and my co-pending applications, Serial Nos. 387,907, filed contemporaneously herewith, 681,183, led July 3, 1946, 683,312, iiled July i3, 1946, and 754,194, iiled June 12, 1947, of which the latter is a division of the present application.

The present .invention is illustrated in connection with special types of gas tubes .with an auxiliary anode. which tubes are also disclosed and claimed in my copending application Serial No. 754,194. iiled June 12, 1947.

Other aspects and advantages of the present invention will become apparent from the ensuing description, in the course of which reference is had to the accompanying drawings, in which:

Fig. 1 is a diagrammatic representation ofla control circuit for a fast operating relay embody- 'ing the present invention;

Fig. 2 is a side elevational view, partly broken away, of a gas tube which may be used in the circuit of Fig. 1;

Fig. 3 is a fragmentary vertical cross-sectional view taken along the line 3 3 of Fig. 2;

Fig. 4 is a view similar to Fig. 3 of another embodiment of the tube; I

Fig. 5 is a fragmentary perspective view of a further embodiment of a tube;

Figs. 6 and Y7 are views similar to Fig. l of other mbodiments of the present invention wherein gas tubes of conventional construction are utilized;

Fig. 8 is a view similar to Fig. l illustrating a further embodiment of the invention;

Fig. 9 is a diagrammatic representation of a standard automobile superheterodyne receiver, in connection with which the present invention has been utilized; and

Fig. 10 is a diagram showing the details of a portion of the circuit of Fig. 9.

The circuit arrangement illustrated in Fig.1 comprises a relay l0 whose energization is controlled by a gas tube li. In order to effect fast operation of the relay, it is constructed to have a low impedance and low inductance winding so that with a given voltage a large current ow through it will be established in a short length of time. The low impedance and inductance are obtained by utilizing low resistance wire and a winding having relatively few turns. Reduction of the number of turns reduces the actuating force exerted by the relay as the number of ampere turns is reduced (assuming the voltage supplied to the relay to remain the same), and to compensate for this reduction and to obtain fast operation the relay winding, indicated by reference character I2, is supplied with a considerable current impulse upon energization by means of a condenser I3 discharging through the winding when tube il is rendered conductive, the discharge iiowing through the tube. This discharge of a large current by the condenser occurs rapidly because of the low impedance of the relay winding and of the gas tube, thereby to effect fast operation of the relay. However, the circuit including the relay winding, tube and condenser has a tendency to oscillate because of its low resistance, and the oscillations reduce the anode potential of the tube and are likely to cause deionization of the gas in the tube and to render the tube non-conductive. These fluctuations are prevented from deionizing the gas in accordance with the present invention, as illustrated in Fig. 1, by providing the tube with an auxiliary anode supplied with a potential suiiicient to maintain ionization of the gas in spite of fluctuations in anode potential.

In addition to the auxiliary anode, indicated by reference character I4, the tube is provided with an anode l5, a grid I6, an indirectly heated cathode I1, and a cathode heater I8. The physical construction of the tube may take various forms, three forms being shown in Figs. 2 and 3, 4, and 5. In the embodiment of Figs. 2 and 3 the tube is shown with the usual glass envelope I9 and base 20. The envelope surrounds the previously enumerated elements of the tube and contains an ionizable gas. The anode I5 is cylindrical in shape and is supported in conventional manner by a pair of spaced posts 2| between insulating plates 22. The cathode I1 is cylindrical in shape and supported concentrically with respect to the anode by a refractory post 23 in which the cathode heater I8 is embedded. The grid I6 is a helical wire located in proximity to the cathode and concentrically arranged with respect to both the cathode and anode. The auxiliary anode I4 is also a helical wire, it being located in this embodiment in proximity to the anode and concentric with respect to the other tube elements. Suitable leads are brought from the tube elements to prongs on the tube base 20. All the vtube elements are of substantially the same length in `order that the tube may operate in its intended manner, as will be described shortly in connection with Fig. l.

The tube illustrated in Fig. 4 is similar to that just described except that the grid and auxiliary electrode are constitutedby metallic cylindrical members 24 Vand 25 provided with `two or more aligned apertures 26 and 21, respectively.

The tube illustrated in Fig. 5 diiers from those previously described mainly in that the grid and auxiliary anode are constituted by apertured nat structural elements 230 and 23|, respectively, and the anodeby a cylindrical wire 232. These elements andthe cathode 233 and cathodeheater 234 are surrounded by a grounded metallic shield 235, the open ends of which are closed by insulating plates 236. The shield comprises an apertured partition 231 located between the grid and auxiliary anode, thus dening two compartments, one for the cathode, cathode heater and grid and a second for the auxiliary anode and anode. The aperturesV in the grid, partition and auxiliary anode are in alignment with each other and the cathode and anode. A tube of this construction may beconstructed simply and economically and possesses a high control factor.

Returning now to a further detailed description of the circuit of Fig. 1, it may be seen that the relay winding I2 is composed of two series connected coils. One terminal of the winding is connected directly to anode I5 by conductor 23 and the other to the positive terminal of a source of potential, such as battery 30, through a current limiting resistor 3| and conductors 32 and 33. The battery thus serves as a source of anode potential for the tube and as a source of energizing current for the relay. The other terminal of the battery is grounded through conductor 34.

The power consumption of the relay is reduced by the resistor 3| which is chosen to have a value such that once the relay is energized, the current flow therethrough is only sumcient to maintain the relay in its operated position.

The current impulse supplying condenser I3 is connected to the cathode by conductor 35 and to a point intermediate the relay and resistor 3l by a conductor 36. It is thus connected so as to be charged by battery 30 when the Vtube is nonconductive and to discharge through the tube and relay when the tube is conductive.-

The auxiliary anode is supplied with a potential suicient to maintain the gas ionized and the tube conductive in spite 'of fluctuations in anode lthe grid more positive and this can be accom- 4 potential from a suitable source, preferably the battery 30, through a current limiting resistor 31 and conductors 38, 39 and 33.

Grid-bias voltage is obtained through the use of an adjustable resistor 40 connected between the cathode and ground. This resistor is connected to the cathode by conductor 4I and to ground through switch 42 andY ground connection 43. The grid is connected to ground through conductor 44, resistor 45 and conductor 46. A grid- Vbias voltage suilicient normally to maintain the tube non-conductive is obtained by connecting the cathode end of bias resistor 46 to the battery through a bleeder resistor 41.

The tube is rendered conductive by rendering plished as by applying a positive signal voltage across the terminals of resistor 45 by means of conductors 48.

'I'he relay may be utilized to controlA circuits or mechanisms and the like. In stop-,on-carrier controls it is utilized to control circuits and a clutch, as indicated in Fig. l. The relay may also take various forms, that shown in Figl 1 beingV of a novel construction requiring but little space.

It comprises a .metallic base 49 having an upg'. turned ange 50 at its front end. The coilsl I2 together vwith their cores 5I are secured to the flange. 'Ifhe cores have upturned ends above which is supported an armature 52 mountedv at the ends of contact carrying switch blades 53 and 54. The switch blades are biased upwardly normally to complete circuits through, fixed switch blades 55 and 56 andare movable down; wardly upon energization of the relayV to complete circuits through switch blades 51 and 58, respectively. The switch blades as wellk as the terminals to which conductors 28 and 32 are attached are mounted at the rear of' base 49 by spacer blocks 59 and suitable bolts. The spacer blocks are made of insulating material to insulate the terminals and switch blades from one another.

Switch blades 53 and 54 are. biasedupwardly by a spring 60 that serves also to maintain the clutch engaged whenever the relay is deenergized. The biasing is eiected through a combined clutch operating and power transmitting rod 6I slidably and rotatably mounted' in a supporting bearing 62 forming part of the base member. The spring is held between the bracket and a washer 63 secured to the rod above the bracket.

The clutch comprises a pair of selectively engageable elements 64 and 65, the former of which is secured to rod 6I and the latter of which is driven from a suitable source of motive power, such as an electric motor, by gear 66. When the clutch is engaged, as indicated, rod 6I is rotated to impart movement to a driven gear 61 used to drive tuning condensers in stop-on-carrier controls, las will be explained more fully in connection` with Figs. 9 and l0. It should be understood, however, that while the circuit described above is particularly adapted for stop-on-carrier controls for radio receivers, it may be used for otherpurposes, as'may be noted from the following description of the operation of the relay and its control circuit. f

In the description of the operation it is assumed that the tube is non-conductive by reason' of the bias applied to grid I6 and that, as a result, relay l0 is deenergized. At this time the grid is biased negatively by reason of current `flow through resistors 40 and 41, which are connected across the battery 30 through conductors 33 and 39, switch 42 and ground connections 34 and 43.

The condenser i3 is fully charged by reason of its connection to the battery and battery potentials are applied to auxiliary anode I4 and anode '.I'he tube is rendered conductive and the gas therein ionized when a positive signal of sufiicient strength is applied across resistor 45, after which the grid I6 becomes ineffective to exert further control. Immediately the tube is rendered conductive, current ows through the relay windings I2 and fast operation of the relay is insured by reason of its low resistance and impedance and the discharge of condenser I3 therethrough. The low resistance series circuit including the condenser, tube and relay winding has a tendency to oscillate with the result that the potential applied to anode I5 may be periodlcally reduced to a value below the potential required to maintain ionization. In the ordinary three element gas tube the result would be the deionization of the tube, but in the described apparatus, the gas in the tube is maintained ionized by the auxiliary anode I4, which is connected to the battery through resistor 31 and which is not affected by the oscillatory circuit.

The relay is supplied with current suilicient to maintain it energized through a circuit including the battery, ground connections 34 and 43, the tube and resistor 3I. Resistor 3I is so proportioned that it limits the relay current to the desired value. Resistor 31 is so proportioned that only a very` limited amount of current ilows through it. thereby reducing power consumption by preventing any substantial ow of current through it and the auxiliary anode in excess of that required to maintain ionization.

When it is desired, to deenergize the relay and to render the tube non-conductive, it is necessary only momentarily to open switch 42. Opening of this switch results in the opening of both the anode and auxiliary anode circuits as the switch is in series with the tube and battery.

In the modification of Fig. 6 there is illustrated a. somewhat diierent arrangement for preventing deionization of a conventional three element gas tube as a result of any tendency of the circuit to oscillate. .This arrangement employs an electrolytic condenser which has a rectifying characteristic-that is, it permits substantial current ow in one direction and substantially prevents current ilow in the opposite direction.

Referring now to Fig. 6, it may be noted that the three element gas tube is indicated by reference character 10. Its anode is connected to the battery 30 (the same reference characters are used to indicate elements of this embodiment corresponding to those in the embodiment of Fig. l) through the winding of relay I0 and current limiting resistor 3I`. Grid biasvoltage is obtained through the use of the bias resistor 40 which is connected between the cathode and ground and to the positive terminal of the B supply battery 30 through bleeder resistor 41. The grid is connected to ground through resistor 45 just as in the embodiment of Fig. 1.

The electrolytic condenser, indicated by reference character 1 I, is connected between the catho de and a point intermediate resistor 3| and the winding of relay I0 by conductors 12 and 13. The condenser thus connected will discharge through the tube and relay winding when the tube is rendered conductive. This connection comprises connecting the anode, which is ordinarily the oxide coated electrode of the condenser, to conductor 13, and the metallic to conductor 12.

When the condenser is connected as indicated and the tube rendered conductive by the application of a positive signal across resistor 45, the condenser immediately and rapidly discharges through the tube and relay winding, thus effecting rapid operation of the relay. However, when a reversal of current through the circuit comprising the condenser 1I and the low impedance relay I II occurs as a result of its tendency to oscillate. a positive potential is impressed on the cathode of the condenser, i. e., the terminal connected to conductor 12, and a negative potential is impressed on the anode of the condenser, i. e., the terminal connected to conductor 13. Under these circumstances the condenser acts as a resistor having a low resistance. Direct current flows through the condenser and large losses occur which damp out the oscillation which tends to reduce the potential applied to the anode of tube 10. Thus, as a result of the unidirectional or rectifying characteristic of the electrolytic condenser, deionization of the gas tube after its original ionization by reason of the tendency of the series circuit including the condenser, tube and relay winding to oscillate, is prevented.

For use in connection with stop-on-carrier radio receivers, such as illustrated in Figs. 9 and 10, the condenser would have a capacity in the order of 1/2 mf. It is desirable that the power factor of the condenser be as high as possible, and it should be formedto withstand, without breakdown, the anode potentials applied to tube 10. It has been found that a condenser of l/2 mf. capacity, having an effective resistance of 250 ohms at cycles per second, operates satisfactorily, although a still lower resistance would be desirable. These values, it should be understood, are merely illustrative and not limitative of the invention.

The embodiment illustrated in Fig. 7 is somewhat similar to that illustrated in Fig. 6 in that it, too, employs the conventional three element gas tube. The condenser employed in this arrangement, however, is an ordinary paper condenser instead of an electrolytic condenser.

Referring now specifically to Fig. 7, it may be seen that the three element tube 10 has its anode connected to the positive terminal of battery 30 through the winding of relay I0 and resistor 15. The paper condenser 16 is connected by conductors 11 and 18 to the cathode and to a point intermediate resistor 15 and the relay winding. The grid of the tube is provided with biasing potential by reason of current owing through an adjustable biasing resistor 19 and a bleeder resistor 80, the grid being connected as in the previously described embodiments to ground connection 43 through resistor 45 and conductors 44 and 46. The normally closed switch 42 is interposed between resistor 19 and ground connection 43. The grid is normally biased negatively with respect to the cathode by reason of current owing from the positive terminal of battery 30 through resistor 15, winding oi relay I 0, resistor 80, conductor 11, resistor 19, switch 42, and ground connections 43 and 34.

In this embodiment the resistance of resistor 15 (which corresponds to resistor 3I of the previously described embodiments) is reduced, so that the flow of current through the relay winding when the tube is ionized is greater than the corresponding current ilow in the embodiment of Fig. 6.

portion, ordinarily aluminum,

By thus reducing the value of the resistor 15, the ow of current through the relay when the tube is ionized is increased. Thus, if the tendency for the circuit, including the relay i0, the

-condenser 16, and the tube to oscillate, is not too great', this tendency will not reduce the plate current sufficiently to lbring the plate voltage below ionizing potential. The current which flows through the resistor 41 in the circuit of Fg. 6, will flow through the tube 10 in the arrangement of Fig. '1, thus providing a larger plate current and requiring a current reversal resulting from oscillation of a higher value in the circuit of-Fig. '1 before thevoltge on the plate falls 'below the ionization voltage. lWhen the tube is deionized, a suicient ow of current through the resistor 19 is maintained through the resistor and the resistor 80, which together have approximately the `same value as the resistor 41 inA the previous embodiment. It will thus be seen `that by thelocationof the resistor 80 in Fig. '1

and lowering the resistance of resistor 1 5, the tendency to deionizecanbe resisted to a greater extent, with the same 'total bleeder current, than entirely from lthe battery 30, i. e., it breaks the circuit lthrough both tube 10 and resistor 80.

In Fig; 8 isr illustrated a further embodiment of the present invention in which an alternating current relay 83 is controlled by a gas tube 84 corresponding to the tube of Fig. 1, but in which the source of energy is an alternating current source rather than a battery. The alternating source (not shown) is connected to the primary winding of transformer 86. "The secondary winding has'one terminal connected to the anode 81 of the tube through the relay and its other terminal to ground through conductor sa..

The auxiliary anode 89 is provided with a substantiallyV lconstant positive potential to maintain the tubeionized after initial ionization has been effected as by application of a suitable signal to grid 90. lThis potential is supplied from a rectifier tube `9| having a iilter condenser 92 connected thereacross. The :anode of tube 9| is connected to the secondary through resistor 93, while the cathode is connected to the auxiliary anode 89 lof tube 84 through conductor 95 and resistor 96. The grid 90 is connected to ground through resistor 91 and conductors 98 and 99. The grid bias voltage is obtained through the use of an adjustable bias resistor |00 connected to the cathode |0| and to ground through normally closed switch |02. The cathode end of the resistor is connected to the positive terminal of the rectifier througha bleeder resistor |03 and conductor 95.

Prior to the application of a positive signal voltage across resistor 91, tube 84 is maintained in a non-conductive condition by reason of the voltage drop across bias resistor |00. The volt'- age`drop results from current ow through the resistor |00 which is connected across the rectifier tube 9| and iilter condenser 92, conductor 95, resistor |03, resistor |00 and ground. At this time a substantially constant potential is applied to the auxiliary anode 88 and an alternating potential to the anode 81. o

When a positive signal is applied across resistor 01 to decrease the negative bias on grid 80, the

tube is rendered conductive and the gas therein ionized. The tube is maintained conductive and the gas ionized, even though an alternating potential is applied to anode 81, by reason of the maintenance of a substantially constant positive potential on auxiliary anode 89. As a result. each half-cycle that a positive potential is applied to anode 81, current flows through relay 93 to maintain it in its operated position.

When it is desired to render the tube non-conductive and release the relay, it is necessary only momentarily to open switch |02.

The'present invention is particularly adapted for stop-on-carrier radio receiver control. The

use of a gas ltube provided withl an auxiliary anode,v results in a reduction of the. number of tubes required. For instance, when used in a control ofthe type disclosed in my copending application one tube is eliminated. An application of', the tube to this type of controlvis illustrated in Figs. 9 and l0. Referring now more particularly to Fig. 9, it may be noted this figure illustrates in block diagram'form a Vstandard automobile superheterodyne receiver to which the elements of the present invention have been added. For the most part the receiver and control circuits are those disclosed and claimed in my copendingapplications Serial Nos. 387,901, (now U. S. Patent No. 2,426,580), 681,183,'683,312, and 754,194, of which. the latter is a division of thisn application an`dconsequently only the por- 'tion of the circuit associated with the operation of the novel gas tube of the present invention will be described in detail hereinafter. i The receiver comprises an aerial H0, a radio frequency stage a first detector and oscillator section |`|2, an intermediatefrequency stage ||3, asecond detector section ||4, a balanced bridge [circuit section ||5 forming part of the stop-'on-carrier control and illustrated in greater detail inFig. 9, a gas tube ||B also forming part of the stop-on-carrier control, a volume 'control potentiometer ||1, an audio'frequency amplifier section H8, and a loudspeaker H9.

Energy is supplied by a battery |20 adapted to be connected by a switch |2| to a tuning means operating motor |22 of the reversible type, a cathode heater circuit |23, and through Ean interrupter, step u p transformer and B supply unit |24l to a B supply line |25. The B supply line leads to the various receiver portions and the stop-on-carrier control in a manner to be considered in greater detail hereinafter. The switchv |2| is illustrated as a manually operable switch, but it may be operated by the motor |22, asset forth in my copending application.

- The receiver is provided with the usual tuning condensers |26 which are actuated by motor |22. The tuning and'receiver volume are controlled from a remote point, such as the dashboard of an automobile, by -means of a tuning control switch |21, which is normally closed, and a volume control switch |28, which is selectively operable from a normal circuit breaking position (into which it is biased as by springs) to the left to increase the volumeand to the right to' decrease the volume. i

Before describing in detail the various control meansand control circuits, it may be Iwell to review briefly themode of operation of stop-oncarrier radio receiver control. In so far as tuning is concerned, the tuning is initiated manually at the remote point by momentary opening of switch |21. Thisl sets the motor in operation torot'ate the tuning condensers through a clutch until the receiver is tuned to the carrier frequency of a station received with a certain intensity. The motor operates first in one direction over the entire range of movement of the condensers and then in the other, the direction of rotation of themotor being controlled by limit switches cooperativelyl associated with the condenser shaft. 'I'he same motor is used to control the volume but, when so used, it is selectively operable in either direction upon operation of switch 28 to either of its two positions. The volume control also includes a clutch through which the motor is selectively connected to the movable portion of the potentiometer |1 heretofore referred to.

Referring again to Fig. 9, it may be noted the condensers 28 are mounted for rotation with a shaft |30 connected by gears |3| to a shaft |32. The latter is adapted to be connected to a shaft |33 driven by motor |22 whenever a relay |34, associated with the stop-on-carrier control, is deenergized or released, at which time the clutch |35 is/engaged. The relay and clutch may be constructed in accordance with those illustrated in Fig. 1, i. e., the relay is of the fast acting type and the clutch is operable by the relayarmature. The energization of the relay is controlled by gas tube ||8 and when it is energized, shafts |32 and |33 are disconnected to prevent further driving of the condensers whenever a station re-v ceived with a certain intensity is tuned in. As already indicated, the tuning condensers are rotated first in one direction and then the other, the direction of rotation being reversed at the limits of their movement by a limit switch |38 operated by two arms or the like |31 suitably secured to condenser shaft |30.

The volume control includes a clutch |38 erable by a relay |38 and adapted whenever relay is energized to interconnect shafts |33 |48. The latter is operatively connected to movable member of potentiometer ||1.

'I'he motor |22 has a pair of windings |4| and |42 selectively energizable to rotate the motor in opposite directions. Winding 4| is connected by' conductors |43 to the right contact of volume control switch |28 and by branch to one of the two contacts associated with limit switch |36. Winding |42 is connected by conopthe and the ductor |45 to the left contact of the volume control switch and by a branch conductor |46 to the other contact of the limit switch. The movable blade of volume control switch |28 is connected by conductor |41 to one terminal of clutch operating relay |38, the other terminal of which is grounded. Thus, when switch |28 is operated to either of its two positions, the motor is energized simultaneously with energization of the relay, and, as a result, the movable member of the potentiometer is operated in one direction or the other to increase or decrease the volume of reception. The energizing circuit is completed in both cases through the armature of motor |22, switch |2|, battery |20 and ground.

The remote tuning control switch |21, which is opened to initiate the tuning of another station, has one of its fixed contacts connected to conductor |41, this conductor serving, as will appear more fully hereinafter, as a ground connection, and its other fixed contact connected to adjustable resistor |48. A conductor |48 connects the latter to the cathode of gas tube ||8 whereby the switch and resistor are included in the plate circuit of the stop-on-carrier gas tube ||6.

The energization of motor |22 during tuning conductor |44 switch |38. Blade |53 is connected by conductor |56 and an AVC delay condenser |51 to an AVC conductor |58. Blade |54 is connected by conductor |58 to the grids of the tubes of the last stage of audio amplification, as in my copending application.

Thus, when relay |34 is deenergized, as it is during the actual tuning operation, the condensers |28 are connected to the motor shaft through clutch |35 and one or the other of the two motor windings is energized, the energizing circuit extending from the battery, through the motor armature, one or the other of windings 4| or |42 depending upon the position of limit switch |38, switch blades |52 and |5|, and ground connection |55 back to the battery. At`the same time conductor |58 and condenser |51 are disconnected from ground to provide fast acting AVC (as described in my copending application), while conductor |58 is connected to ground through switch blades |5| and |54 and conductor |55. Connection of conductor |58 to ground serves to connect the grids of the amplifier tubes of the last amplifier (audio-frequency) to ground to mute the loudspeaker during tuning. When the relay is energized by tube ||8 becoming conductive, as now about to be described, the condensers are declutched from the motor and the latter ,deenergized The motor is deenergized by reason of the opening of its energizing circuit by disengagement of blades |50 and 52. The AVC delay condenser 51 is simultaneously rendered effective to increase the time delay applied to the AVC voltage to a value necessary for proper reception during normal reception. Furthermore, the ground is removed from the audioffrequency amplifier tubes to condition these for normal operation.

The primary function of gas tube ||8 is to control the energization of relay |34 so thatit is substantially instantaneously operated when the receiver is tuned to the carrier frequency of a broadcast station. A further function of this .gas tube, whichv is provided with an auxiliary vent premature. deionization of the tube as 'a -has been ionized. To fulll result of oscillations in the plate circuit after it this function, the gas tube ||8 operates in a manner somewhat similar to thatdescribed in connection with Fig. l. The relay is energized when the tube is rendered conductive and the latter is rendered conductive whenever the condensers |28 are rotated to tune the receiver to the carrier 'frequency of a broadcast station. To insure the tube being rendered conductive when the station is exactly tuned in, the tube is controlled in response to the tuning. In brief, the tube ||6 is controlled by two potentials, one acting upon the auxiliary anode |11 and the other upon a grid 2|2. These potentials vary with the tuning of the receiver and render the tube conductive when the station is substantially exactly tuned to a carrier frequency.

Referring' now-more particularly to Fig. 10, this figure illustrates in greater detailcertain portions of the apparatus illustrated diagram- The 4radio frequency section of'Fig. 9 is shown to comprise a tube |1|. Its controlgrid is coupled in conventional manner to th'e antennaV by conductor |12 and connected'to the lAVC con ductor |58 through resistor |13. Its anode ls connected to the primary winding |14 of a coupling transformer which has not beenl illustrated in full but which is utilized to connect tube |1| tothe first detector and oscillator section H2, which likewise has not been illustrated in Fig. 9. The Vterminal'of'winding |14 remote Yfrom the anodejis connected to the B supply conductor |25 throug'hconductor |15 and resistor |16 and to the aujziliary anode- |11 of the gas tube through conductor |15 and a resistor |18, The sameterminal is also by-passed to ground through condenser |11a.

The automatic vvolume control includes a resistor |19 connected between conductor |58 and a conductor |80 leading to a source of AVC voltage to be referred to later. It also includes a very small radio frequency by-pass condenser |8| connectedbetw'een conductor |58 and ground and the' previously mentioned AVC time delay condenser |51 that is controlled by switch blades |50 andl53 operated by'relay |34.

The output from' the Vradiofre\. 1uency section 1:0A are indicated by like reference 12 fact, and as will appear shortly, tube Y|88 ls utilized also as a rectier to provide a second control potential for gas tube I6.

The second control potential `for gastube v|16v is obtained by means of a balanced bridge circuit 200 so constructed and arranged that it is critically responsive to the tuning of. a station. as fully described in my copendng applications Serial Nos. 387,907 and 683,312. This circuit comprises a first tank circuit including primary winding |83, condenser 20 I, condenser 202, resistor 203,.

and an adjustable condenser 204, whereby this circuit may be tuned to resonance at the intermediate frequency. 'I he circuit also comprises a second tank circuit including condenser 202, inductance coil 205 and anadjustable condenser 206 for tuning this tank circuit to rescnance'fatV the intermediate frequency. The common connection of condensers 20|, 202 and 206 is grounded.- The common side of winding |83 and con` denser 204 is connected to the common side of inductance 205 and condenser 206 throl'ighgcone denser 201. f

The outpu from the bridge circuitr'isled to? the anode 208 of the second diode rectifier section of tube |86 through a condenser 209andconf ductor 2|0, and the rectified output appearingras a voltage drop across resistor 2|| is supplied'to the control grid 2 I2 of gas tube I6 through a time'j delay circuit including the resistor 2|2' andcon-l denser 2|3. The resistor 2|2' is in series with the grid lead 2|4 connecting the grid to the anode is, as alreadydescribed, supplied tothe first detector'andoscillatorsection ||2 and thenceA The intermediate frequency section comprises` a tube |82,l the anode of which is connected to one terminal of the primary winding |83 of a closely coupled transformer, the other terminal of which is connected to B supply conductor |25 A portion of the outputof tube |82 is supplied to the detector stage through the secondary winding |84 `of the transformer. One terminal of winding |84 iishconnected to the detector anode |85 of a multi-function tube |86 through conductor |81', and the other terminal by conductor |88 to volume control resistor ||1, which is shunted by condenser |89 and together with the detector diode section of tube |86 serves also as the source of AVC voltage. The other terminal of resistor ||1 is connected to the cathode |90 of tube |86 by a grounded conductor |9|. i

vTube |86 also serves as the rst stage of battery |93,'conductor |84 and condenser |95.

The grid is further connected to ground by a grid leak resistor |96. The amplified audio-frequency output is supplied to the succeeding stage of amplification through the anodev connection |91. From the foregoing description it may be noted that the circuit of Fig. 10 does not'cor're-l spond exactly to the block diagram of Fig. 9, in that in the latter the second detector and audiofrequency amplifler'sections have been entirely separated. However, in a practical installation the tube |86 may well perform the dual function of a detector and amplifier, and it has been illustrated as doing this in Fig. .10. As a matter of end of resistor 2||.

ductor |9| and the previously referred to con-` ductor |49 leading to the cathode 2|6 of gas tube The relay |34 is connected to anode 2|6 of tube ||6 by conductor 2|9 and the B supply is connected to the anode through the relay winding l and current limiting resistor 220. A current im`- pulse is supplied to the relay Winding when the i tube is rendered conductive by a condenser 22| having one terminal connected to the cathode' 2 6 through conductor |49 and its other terminalV connected to a point intermediate relay winding)- |34 and resistor 2120. A bleeder resistance 222,

connected at one end to the B supply and at the other end to the cathode leadA |49, provides,

cuit for motor |22 extending from the battery |20,

switch |'2|, the amature of motor |22, winding |42, conductors |45, |46, limit switch |36, switch blades |52, |50,and back to the battery through ground connection |55. Since clutch |35 is engaged when relay |34 is deenergized, as it is at this time, the motor rotates the condensers |26 first in one direction and then the other as the windings |4| and |42 are alternately energized by operation of limit switch |86from'one position to another by the arms |31 mounted on condenser shaft |30. This rotation of the condensers in alternate directions continues until the various tubes are heated and a broadcast station received. When a station is received, the gas tube ||6 is rendered conductive and relay |34 immediately operated to declutch the condensers from the motor shaft and to deenergize the motor.

The gas tube is rendered conductive `by the ap- A radio frequency by-pass condenser 2|5 is connected across ground con^v plication cian; increased positive potential on the auxiliary nde |11 and by a reduction of the negative voltage impressed on the grid 2|2 from the diode 206. The auxiliary anode is made more positive as a result o1' thel application oi' automatic volume control voltage tothe grid of radio frequency tube |1|. This control voltage is obtained i'rom the second detector section of tube |36 and is applied to the grid of tube |1| through a circuit including conductor |60, resistor |19, conductor |58, resistor |13, and conductor |12. As a result of the application of this control voltage on the grid of tube I 1|, the plate current of this tube is decreased, with the further result that the voltage drop across resistor |16 is decreased and an increased the auxiliary anode |11, which is connected to the anode side of resistor |16. This connection is through resistor |18 which serves to limit currentI flow through the auxiliary anode. The voltage applied to the auxiliary anode rises rapidly as a station is being tuned in and is at a maximum when a station is exactly tuned in, as described at considerable length in my copending applications Serial Nos. 387,907 and 683,312.

The voltage thus applied to the auxiliary anode |11 when'ionization occurs is considerably in excess o! the ionizing potential, and remains so until the next station is tuned in by manually operating push' button switch |21, to deionize tube III. Thus, even though oscillation in the circuit, including tube ||'6, relay |34, and condenser 22|, may reduce the voltage of the plate 2|8 below ionizing potential, ionization is maintained regardless of the potential on the plate by the potential on the auxiliary anode |11, which remains continuously above the ionizing potential until the switch |21 is again opened.

The balanced bridge circuit 200 supplies a signal to the diode 208 which increases as resonance with the station is approached until it is within about one kiiocycie -of resonance. From this point the amplitude of this signal falls rapidly, substantially to zero. Thus, a negative direct current voltage from the diode 208 is applied to the grid 2|2 of the gas tube ||6, which increases as resonance is approached to a maximum negative value around one kiiocycie from resonance, and then falls steeply substantially to zero at resonance. The reduction of this negative signal on the grid 2|2 when the station is correctly tuned in, together with the previously described increase in the positive voltage applied to the auxiliary anode |11, eil'ects ionization of the tube ||'6 and stopping of the condensers |26 at a position correctly to tune in the station.

The primary winding |83 of the transformer associated'with the intermediate frequency tube |32, condenser 204, resistance 203, condenser 202, and the mutual reactance of condenser 201 constitute a tank circuit tuned to the intermediate frequency. Condenser 202, inductance 205, condenser 206, together with the mutual reactance of condenser 201, also constitute a tank circuit tuned to the intermediate frequency. This circuit is excited through condensers 202 and v201. The coupling of these tank circuits through condenser 202 is inversely proportional to the frequency, while the coupling through condenser 201 energizing the inductance 205 is proportional to the frequency. Due to these opposing couplings and the parameters of the elements of the two tank circuits. the potential appearing across condenser 206 is substantially zero when a signal of exactly intermediate frequency is placed across the pripositive potential is applied to of switch blades |50 and mary winding |83. In other words. the eilect of the coupling occurring through condenser 201 produces a voltage drop across the inductance 205 which is equal and opposite to the voltage drop across condenser 202 at resonance. The value of resistance 203 is selected so as to bring the voltage across the condenser 202 out of phase with the voltage across inductance 205. Under these conditions there is substantially zero voltage across condenser 206 at resonance. In one aspect the arrangement of the coupled circuits when the negative bias applied to the grid 2|2 resonance) so that tuned in, the tube is rendered conductive by the conjoint actions of the less negative grid and more positive auxiliary anode |11. When the tube H 6 is ionized, the plate to cathode resistance of the tube drops to a relatively low value. condenser 22|, which accumulates a high charge through its connection to the "B supply through resistor 220 during the non-conductive period of tube 2|6, now discharges rapidly through the low impedance Winding of relay |34, with the further result that the relay is instantly operated to declutch the condensers from the motor shaft and to deenergize the motor, thus stopping the condenser exactly on the carrier frequency as previously explained. The steady ilow of current through the resistor 220, relay winding and tube, which are connected in series across the B potential, is suilicient to hold the relay in its operated position once it has been operated by the discharge of condenser 22|.

As heretofore explained, the operation of the switch of relay |34 results also in the disconnection of conductor |59 from ground, thereby removing the ground connection from the last stage of audio-frequency amplication, and the output of the receiver can be heard through loudspeaker H9. The relay also effects connection |53, with the result that condenser |51 is connected to ground to render it effective to increase the time delay applied to the automatic volume control voltage necessary for proper quality reception during audible reception of the signal.

When it is desired to tune in a different station, switch 1| 21 is momentarily opened, thereby effectively breaking the plate circuit of the gas tube which results in the deenerization of relay |34. The motor is thereby Penergized and the of the gasftulie.

control'thexnormal negative bias o i the grid2ll2 'adjusted `at will by meansl The volume may be adjusted at any time by moving the volume control vswitch [2B .either .to the rightor left, as indicated in Fig. 9...Wh en moved into either of its circuit making positions,

theo-ne or" the other of motor windings lli, or

'H2 is energized simultaneously lwith theenergization' 'of clutch ,operating solenoid,139.. The energization of the solenoid results in tlieclutchfingo'f the volume control shaft llilto the motor shaftl 133 withthe result, that the movable nieinberof the volumec'ontrol potentiometer .i i1

is operated in the direction selected bybperatio'n of'thefvolume control switch, 128. i Y

y When vit is desired to turn the receiver, ofi, it .is necessary onlyVY to' open vthe vpower switch m which enecnveiy cuts' onine power tothe radio receiver proper and to the vvarious controls. .Q VAlthough the invention hasbe'en disclosed in connection with speciilc details of preferred embodiments thereof, it. mus't be lunderstood that such details are not intended' tn be .limitative or the invention except in so far, as, setiorth in the accompanyingclaims,v 'A Having thusdescribed `y inventiomvvhat4 I claim as new and, desire 1tosecure byLetters Patentpf the United States is;

l1.` In, combination,. a cathode.. anode,v gridand an Lauxiliary anode, means for supplying.` said .auxiliary anode with potential sulcient to. maintain the ionization of as tube' comprising n thegas'in said tube oncefthe tube has-beenionized, and means for supplying control potentials to both said grid and auxiliary anode for ionizing thegasinsaidtube.

2. In combination, a gas tube comprisingv a cathode, anode, grid, andan auxiliaryanode, a source of. anode potential, means for-,normally supplying said grid with a negative potential suf. cient to prevent ionization of the gas in said tube, a source of positive potential rorfsaid auxiliary anode forf maintaining ionization of the tube once .it has been ionized, and means vfor varying both thegrid and auxiliary anode potentials to ionize the gas in said tube. Y.

v3. In` combination, a vgas tube Acomprising a cathode, anode,` grid, and an auxiliary anode,

a source of kanode potential, means for normally supplying saidgrid with a negative potential.; suf. ilcient to prevent ionization ofthe gas in said tube, a source of positive potential for said auxiliary anode, and means for varying both the grid and auxiliary anodefpotentials to yionize the gas in said tube, the source of positive potential for said auxiliary anode being such that said auxiliary anode maintains ionization of the gas irrespectivel of -variations in potential of said anode potential.

4. In combination, va low inductance relay, a

gas tube comprising a cathode and anode in circuit with said relay, a source of anode potential connected to the anode of said tube through said relay, means for ionizing they gas in said tube to energize said relay, means including a condenser dischargeable through said relay and tube upon ionization ofy said tube for effecting quick opera- --tom'aintain-ionization.

f5. In combination, v'a fast acting relay ofI A type comprising a low impedance windingof. relativelx)Y few turns of wire, a gas tube comprising an anode and cathode, a source of 'direct currenthaving its positive terminalconnected tosaid anode through said'relay winding andfi'ts negative terminal connected to said cathode, aeiijgngnm.. itingresistor'in circuit between the positive terminal of'said source and said'jwinding, al condenser .connected 'acrosssaid cathode Yand 'a'. point linter- 'me'diate said resistor and relay-winding, said condenser and relay comprising "together'with said t'ubealow resistance oscillatory circuit, means 'for ionizing the gas in saidtube 'to discharge the condenser through saidrelay, and means for maintaining-said relay energized despite fluctuations -in anode potential causedby oscillation Ain'said oscillatory circuit. 'l s 6. vIn combination,'af-fast acting relay ofthe type comprising ay low' impedance winding offew turns'av gas tubecomprising an anodercathode. grid, and auxiliary anode, said grid and auxiliary anode being spaced apart and lcatedin proximity to said cathode and ano'deya directcurrent'source of anode potential, a circuit includingy a resistor and said relay winding connecting the positive terminal of said potential source to vsaid anode, lsaid resistor limiting" the current flow through said winding to a value sulcient to maintain the relay in operated position after initial operation thereof, a circuit from the Vnegativeterminal of said potential source-to said cathode 'including a grid biasing resistoiia condensenconnected across' said cathode and a point intermediate the source and relay winding foreiecting initial operation' of the'relayby a current impulse'when saidtube is ionized, said condenser, relay winding, and ftube constituting as oscillatory circuit, means associated with said gridforionizing thegas in4 said tube, means-including 'a connec-v tion from'the positive terminal of said potential source to said'auxiliary anode having interposed therein a current limiting resistor for preventing theV voscillation in said oscillatory circuit from deionizing the gas in said tube, and means f or de' ionizing the'gas in thetube including a switch in circuit with said potential source; I

7.`In combination, va fast acting relay (of the type comprising a low impedance winding of relatively few turns of wire, `a gas tube y comprising an anode, cathode, and grid, a direct vcurrent sourcefof anode potential, a circuit including' a" resistor and said relay winding connecting the positive terminal of said potential source to said anode, said resistor limiting the current flow through said winding to Ka value suiilcient to maintain the relay in loperated position after initial operation thereof, a' circuit from thenegativeterminal of said potential source to said cathode', an electrolytlc condenser connected across:

said cathode and a point intermediate said relay winding and the positive terminal in such man-v ner that when the tube is ionized it discharges' through the tube 'and winding to effect initial condenser, thus preventing deionization by reduction of anode potential due to oscillation,` and means associated with said grid for ionizing said tube.

8. In combination, a fast acting relayof the type comprising a low inductance winding, a gas tube comprising an anode, cathode and grid, a direct current source of anode potential, a circuit including a resistor and said relay winding connecting the positive terminal of said potential source to said anode, said resistor providing a current 110W through said winding above a value suillcient to maintain the relay in operated position after initial operation thereof, a circuit from the negative terminal of said potential source to said cathode including a grid biasing resistor, a condenser connected across said cathode and a point intermediate said relay winding and the positive terminal for effecting initial operation of the relay by a current impulse when said tube is ionized, said condenser, relay winding, and tube constituting an oscillatory circuit, a bleeder resistor connected between said cathode and a point intermediate said relay winding and'anode, said resistor providing grid biasing current during deionization of said tube, means associated with said grid for rendering said tube conductive, and means including a switch in circuit with said potential source for deionizing said tube.

9. In combination, a gas tube comprising a cathode, anode. grid, and auxiliary anode, said grid and auxiliary anode being spaced apart and located in proximity to said cathode and anode, a relay winding, an alternating current source of anode potential, a circuit including said relay winding connecting said source to said anode and cathode, means including said grid for ionizing the gas in said tube, means including a direct current source, the positive terminal of which is connected to said auxiliary anode, for maintaining ionization o! said tube, and a current limiting resistance in series with said auxiliary anode and said direct current source.

10. In combination, a gas tube comprising a cathode, anode, grid, and auxiliary anode, said grid and auxiliary anode being spaced apart and located in proximity to said cathode and anode, a relay winding, an alternating current source of anode potential, a circuit including said relay winding connecting said source to said anode and cathode, means including said grid for ionizing the gas in said tube, means includinga direct current source, the positive terminal of which is connected to said auxiliary anode, for maintaining ionization of said tube, a current limiting resistance in series with said auxiliary anode and said direct current source, and means including a switch in circuit with said alternating current source for deionizing said tube,

11. In combination, a gas tube comprising a cathode, anode, grid and auxiliary anode, an alternating current source of anode potential connectedto said anode, means including said grid for ionizing said tube, and means including an auxiliary anode for maintaining ionization of said tube when the alternating current potential applied to the anode is insuiilcient to do so.

12. In combination, a fast acting relay of the type comprising a low impedance winding, a gas tube comprising an anode, cathode, grid and auxiliary anode, said being spaced apart and located in proximity to said cathode and anode, a direct current source of anode potential, a circuit including a resistor and l said relay winding connecting the positive terminal of said potential source to said anode, said resistor limiting the current flow through said winding to a value suiiicient to maintain the relay in operated position after initial operation thereof, a circuit from the negative terminal of said grid and auxiliary anodev relay winding for effecting initial operation of the relay by ionized, said having interposed therein a current limiting resistor for preventing the oscillation in said oscillatory circuit from deionizing said tube.

13. In combination,

having in series therewith the resistor and relay winding, a condenser connected across said cathode and a point intermediate said resistor and relay winding, whereby said condenser is adapted .to discharge through the tube and relay upon ionization of the tube to effect quick operation of the relay, and said condenser, relay and tube comprising an oscillatory circuit, means for ionizing the gas in said tube to discharge the condenser through said relay, and means for maintaining said relay energized despite iiuctuations in anode potential subsequent to the energization of said relay.

14. In combination, a fast acting low inductance relay, a gas tube comprising an anode, cathode, and grid, a direct current source of anode potential, a circuit including a current limiting resistor and said relay `winding connecting the positive terminal of said potential source to said anode, a circuit from the negative terminal of 'said potential source to said cathode, an electrolytic condenser connected across said cathode and a. point intermediate said relay winding and the positive terminal so that it discharges through the tube and relay winding when the tube is ionized, and means for ionizing said tube.

15. In combination, a gas tube comprising a cathode,` anode, alternating current source of anode potential connected to said anode, means including said grid for ionizing said tube, and means including a rectiiier energized from said alternating current source and having its output connected to said auxiliary anode for maintaining ionization of said tube when the alternating current potential applied to the anode is insuiiicient to do so.

16. In combination, a gas tube comprising a cathode, anode, grid and auxiliary anode, an alternating current source of anode potential connected to said anode, means including said grid for ionizing said tube, and means including a half -wave rectifier and iilter condenser connected to said alternating current source for supplying said auxiliary anode with direct current to maintain ionization of said tube when the alternating current potential applied to the anode is insuiiicient to do so.

17. In combination, a gas tube comprising a cathode, anode, grid, and an auxiliary anode, a source of anode potential, means for supplying said grid with a negative restraining potential sufficient to prevent ionization of the gas in said tube, a source of relatively high positive potential for said auxiliary anode, and means for reducing the negative potential supplied to the grid and for increasing the positive potential applied to said auxiliary anode to ionizerthe gas in said tube.

a current impulse when said tube is grid and auxiliary anode, an4

18. In combination, an electron tube having an output circuit and a grid, resistance means in said output circuit, meansv connected to the grid of said tube for rendering the grid more negative and thereby making the anode end of said resistance means more positive, a gas tube comprising a cathode, anode, grid and auxiliary anode, a relay in the anode circuit of said gas tube, a source of anode potential connected to the anode of said gas tube through said relay, means for normally biasing the grid of said gas tube negatively to a potential sumcient to prevent ionization of the gas in said tube. and means including a connection from the plate end of said resistance means to the auxiliary anode of said gas tube for supplying a positive potential to the auxiliary anode and increasing the positive potential applied to the auxiliary anode to control the ionization of said tube. 19. In combination, a gas tube comprising a cathode, anode, grid and auxiliary anode, a source of i alternating current anode potential in the anode-cathode circuit of said tube, a utilization device in said anode-cathode circuit, means including said grid for ionizing said tube to operate said utilization device, and means including a rectiiier energized from said alternating current source and a lter including impedance means in its output circuit for connectingthe positive output terminal of the rectifier to the auxiliary anode for maintaining ionization of said tube during that part of the cycle when the alternating current potential applied to the anode is insuiicient to do so and for restricting the power supplied from the rectifier.

20. In combination, a gas tube comprising a cathode, anode, grid and auxiliary anode, a source of alternating current anode potential in the anode-cathode circuit of said tube, a utilization device in said anode-cathode circuit, means including said grid for ionizing said tube to operate said utilization device, a rectifier and lter energized from said alternating current source, means for supplying a positive, ltered direct current voltage from the rectier and lter to the auxiliary anode for maintaining ionization of said tube during that part of the cycle when the alternating current potential applied to the anode is insumcient to do so, means for deionizing said tube, and impedance -means between the cathode and grid of said tube and between the cathode and said rectier and lter to bias the grid of said tube so that it tends to maintain the tube deionized.

2l. In combination, a. gas tube comprising a cathode, anode, grid, and an auxiliary anode, a source of anode potential, means for supplying said auxiliary anode with positive potential, means for supplying said grid with negative ionization restraining potential, and means supplying variable control voltages to the grid and auxiliary anode for varying the grld and auxiliary anode potentials to ionize the gas in said tube.

22. In combination, a gas tube comprising a. cathode, anode, grid, and an auxiliary anode, a source of anode potential, means for supplying said auxiliary anode with positive potential,

means for supplying said grid with negative ionization restraining potential, and means for varying the grid and auxiliary anode potentials to ionize the gas in said tube, said lastmentioned means includingmeans for increasing the positive potential of the auxiliary anode and means for increasing and then decreasig the negative potential of the grid.

WILLIAM J. OBRIEN.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS 

